Clinical efficacy of intraoral ultrasonography versus transgingival probing for measurement of gingival thickness in different gingival biotypes: a clinical trial.

BACKGROUND: Transgingival probing is conventionally used for gingival thickness (GT) measurement. However, invasiveness is a major drawback of transgingival probing. Thus, researchers have been in search of alternative methods for measurement of GT. This study compared the clinical efficacy of intraoral ultrasonography and transgingival probing for measurement of GT in different biotypes. MATERIALS AND METHODS: This clinical trial was conducted on 34 patients requiring crown lengthening surgery. GT was measured at 40 points with 2- and 4-mm distances from the free gingival margin (FGM) of anterior and premolar teeth of both jaws in each patient by an intraoral ultrasound probe. For measurement of GT by the transgingival probing method, infiltration anesthesia was induced, and a #25 finger spreader (25 mm) was vertically inserted into the soft tissue until contacting bone. The inserted length was measured by a digital caliper with 0.01 mm accuracy. All measurements were made by an operator with high reliability under the supervision of a radiologist. Data were analyzed by t-test, Power and Effect Size formula, and intraclass correlation coefficient (ICC). RESULTS: The two methods were significantly different in measurement of GT in both thick and thin biotypes at 2- and 4-mm distances (P < 0.001). The two methods had a significant difference in both the mandible (P < 0.001) and maxilla (P < 0.001) and in both the anterior (P < 0.003) and premolar (P < 0.003) regions. Although the difference was statistically significant in t-tests, the power and effect formula proved it to be clinically insignificant. Also, the ICC of the two methods revealed excellent agreement. CONCLUSION: The results showed optimal agreement of ultrasound and transgingival probing for measurement of GT. TRIAL REGISTRATION: The study was approved by the ethics committee of Shahid Beheshti University of Medical Sciences on 2021-12-28 (IR.SBMU.DRC.REC.1400.138) and registered in the Iranian Registry of Clinical Trials on 2022-03-14 (IRCT20211229053566N1).

Accuracy comparison of single- and double-sleeve endodontic guides for fiber post removal.

BACKGROUND: This study aimed to assess the accuracy of two different endodontic guides for fiber post removal. METHODS: In this in vitro study, 54 maxillary canine fiber posts were mounted on 36 maxillary stone casts; 18 teeth were mounted unilaterally, and 36 teeth were mounted bilaterally. Static endodontic guides were fabricated according to baseline cone-beam computed tomography (CBCT) and intraoral optical scans using Blue Sky software. In the single-sleeve endodontic guides group (SSG), two anterior and two posterior teeth were included in a 5-unit guide. In the double-sleeve endodontic guides group (DSG) group, the guide was passed through the midline to include both canine teeth and extended by 2 teeth posterior to the canine teeth bilaterally (a 10-unit guide). After drilling, postoperative CBCT scans were taken and superimposed on the virtually designed path, and the maximum coronal deviation (MCD) at the marginal entry point of the tooth, maximum apical deviation (MAD) at 10 mm apical to the tooth margin, and maximum angular deflection (MAnD) of the drill were calculated. RESULTS: The mean MCD, MAD, and MAnD were 0.34 mm, 0.6 mm, and 2.32 degrees, respectively, in the SSG and 0.31 mm, 0.7 mm, and 2.37 degrees, respectively, in the DSG. The two groups were not significantly different from each other in terms of MCD (P = 0.573), MAD (P = 0.290), or MAnD (P = 0.896). CONCLUSIONS: The accuracies of the two techniques, the extended double sleeve guide and the single sleeve guide, were comparable and thus DSG may be used for removal of fiber posts in adjacent or distant teeth.

Relationship between Impacted Mandibular Third Molars and the Mandibular Canal on CBCT Scans.

This study aimed to assess the relationship of impacted mandibular third molars with the mandibular canal on cone beam computed tomography (CBCT) scans. This cross-sectional study was conducted on CBCT scans of 137 patients with 204 impacted mandibular third molars. The relation of age, gender, class of impaction, anatomical position of canal relative to tooth (buccal, lingual, inferior, inter-radicular), tooth angulation (mesioangular, vertical, distoangular, horizontal), relationship of tooth with the mandibular canal (no contact, in contact, relation), relationship of tooth with the mandibular cortex, anatomical site of contact of tooth with the mandibular cortex (buccal, lingual, inferior), and the impression of canal (grooving, no effect) on impacted teeth were evaluated. Data were analyzed using one-way ANOVA, Chi-square test and Fisher's exact test. Class B of impaction (78.9%), inferior position of canal relative to the impacted tooth (53.9%) and mesioangular angulation (53.4%) had the highest frequency, respectively. The relationship of tooth with the mandibular canal was "relation" in most cases (53.4%) followed by no contact (26.9%) and in contact (19.6%). Significant associations were noted between depth of impaction (P < 0.001), tooth angulation (P = 0.024), anatomical position of canal relative to tooth (P < 0.001), relationship of tooth with the mandibular cortex (P = 0.032) and anatomical site of contact of tooth with the mandibular cortex (P = 0.013) with the impacted tooth-mandibular canal relationship. CBCT provides accurate information about the relationship of impacted third molars with the mandibular canal and can decrease the risk of traumatization of inferior alveolar nerve (IAN) during their surgical extraction.

The association of endodontic prognostic factors with the presence of periapical lesion, its volume, and bone characteristics in endodontically treated molars: a cross-sectional study.

BACKGROUND: This study intended to evaluate the association between several endodontic prognostic factors with the presence of periapical lesions (PLs), their volume, and bone characteristics including cortical bone destruction (CBD) and buccal plate bone height (BPBH) in root-filled molar teeth using cone-beam computed tomography. METHODS: A collection of 143 scans of endodontically treated maxillary/mandibular first or second molars recorded over 8 years, were obtained from a specialized radiology center. Data on prognostic factors including tooth number, gender, jaw type, the status and number of missed canals, obturation length, restoration type, presence of a separated instrument, presence of a post or screw in the canals, and presence of perforation were collected. The assessed outcomes included PL presence, PL volume, CBD, and BPBH. The association between prognostic factors and outcomes was evaluated using multiple logistic regression models with adjusted covariates and multifactorial ANOVA at a significance level of 0.05. RESULTS: A total of 282 molars from 82 women and 50 men with a mean age of 40.6 ± 12.27 were included. Among those, 139 teeth presented PL with a mean volume of 18.68 mm3. CBD was prevalent in 137 teeth and the mean BPBH appeared to be 9.45 mm. The presence of a missed canal (OR = 10.022, P < .05), underfilled canal (OR = 3.725, P < .05), overfilled canal (OR = 15.859, P = .018), and perforation (OR = 15.261, P = .013) was significantly associated with PLs. None of the prognostic factors could considerably contribute to the CBD (P > .05). The presence of a missed canal was positively associated with the PL volume (P < .05). Similarly, missed canals (P < .05), perforation (P < .05), and separated instruments (P = .004) were associated with a significantly reduced BPBH. CONCLUSIONS: Overfillings, perforations, missed canals, and underfillings were identified as remarkable predictors of PL, arranged in descending order of their respective impact. The only factor capable of significantly increasing the PL volume was the missed canal. In brief, obturation length errors, perforations, missed canals, and separated instruments were robustly correlated with endodontic failure, which highlights the importance of mitigating the potential for errors by following the fundamentals of endodontics.

Evaluation of diagnostic accuracy of cone beam computed tomography and multi-detector computed tomography for detection of anatomical variations in rhinoplasty.

BACKGROUND: Different imaging techniques, such as multi-detector computed tomography (MDCT) scan and cone beam computed tomography(CBCT), are used to check the structure of the nose before rhinoplasty. This study aimed to evaluate the accuracy of two imaging techniques, MDCT scan, and CBCT, in diagnosing structural Variations in rhinoplasty for the first time. METHODS: This diagnostic accuracy study was conducted on 64 rhinoplasty candidates who complained of snoring and sleep apnea or had a positive result in the examination with Cottle's maneuver or modified Cottle technique between February 2021 and October 2022 at 15- Khordad Hospital affiliated to Beheshti University of Medical Sciences. Before rhinoplasty, patients were randomly assigned to one of the CT and CBCT techniques with an equal ratio. Scans were assessed for the presence of Nasal septum deviation (NSD), Mucocele, Concha bullosa, and nasal septal spur by two independent radiologists. The findings of the two methods were evaluated with the results during rhinoplasty as the gold standard. RESULTS: NSD was the most common anatomical variation based on both imaging techniques. The accuracy of CBCT for diagnosing Nasal Septum Deviation and Mucocele was 80% and 75%, respectively. The sensitivity, specificity, and accuracy of CBCT in detecting Concha bullosa were 81.3% and 83.3%, respectively. The Kappa coefficient between CBCT and intraoperative findings for diagnosing NSD and Concha Bullosa was 0.76 and 0.73, respectively (p < 0.05). CONCLUSION: CBCT can be considered a suitable method with high accuracy and quality to evaluate the anatomical variations before rhinoplasty.

Comparative Diagnostic Accuracy of VistaCam IX Proxi and Bitewing Radiography for Detection of Interproximal Caries.

Statement of the Problem: Early detection of caries and the extent of carious lesions for appropriate treatment planning are very important and lead to introduction of new diagnostic tools. Purpose: This study aimed to compare the diagnostic accuracy of VistaCam IX Proxi and bitewing radiography for detection of posterior interproximal caries. Materials and Method: This in vitro study was performed on 40 extracted posterior teeth without cavitated carious lesions. Bitewing radiographs were obtained, infrared (IR) examination was performed, and the teeth were sectioned for histopathological analysis under a stereomicroscope as the gold standard for detection of caries and determination of the extent of carious lesions. Data were analyzed with Cohen's kappa statistic, and Wilcoxon rank sum test. Results: The specificity of VistaCam IX Proxi and bitewing radiography was 71.4% and 87.7%, respectively. Their sensitivity was 100% and 40% for enamel caries, 72.8% and 54.5% for external half dentin caries, and 82.3% and 58.8% for internal half dentin caries, respectively (p= 0.048). Conclusion: Bitewing radiography had a higher specificity and lower rate of false positive results. However, VistaCam IX Proxi had higher sensitivity for caries detection with lower rate of false negative results. Considering the higher sensitivity and significantly lower frequency of false negative results by VistaCam IX Proxi, it may be reliably used for caries detection specially enamel caries, and can serve as an adjunct to bitewing radiography.

Assessment of CBCT gray value in different regions-of-interest and fields-of-view compared to Hounsfield unit.

OBJECTIVES: Different factors can affect the discrepancy between the gray value (GV) measurements obtained from CBCT and the Hounsfield unit (HU) derived from multidetector CT (MDCT), which is considered the gold-standard density scale. This study aimed to explore the impact of region of interest (ROI) location and field of view (FOV) size on the difference between these two scales as a potential source of error. METHODS: Three phantoms, each consisting of a water-filled plastic bin containing a dry dentate human skull, were prepared. CBCT scans were conducted using the NewTom VGi evo system, while MDCT scans were performed using Philips system. Three different FOV sizes (8 × 8 cm, 8 × 12 cm, and 12 × 15 cm) were used, and the GVs obtained from eight distinct ROIs were compared with the HUs from the MDCT scans. The ROIs included dental and bony regions within the anterior and posterior areas of both jaws. Statistical analyses were performed using SPSS v. 26. RESULTS: The GVs derived from CBCT images were significantly influenced by both ROI location and FOV size (p < 0.05 for both factors). Following the comparison between GVs and HUs, the anterior mandibular bone ROI represented the minimum error, while the posterior mandibular teeth exhibited the maximum error. Moreover, the 8 × 8 cm and 12 × 15 cm FOVs resulted in the lowest and highest degrees of GV error, respectively. CONCLUSIONS: The ROI location and the FOV size can significantly affect the GVs obtained from CBCT images. It is not recommended to use the GV scale within the posterior mandibular teeth region due to the potential for error. Additionally, selecting smaller FOV sizes, such as 8 × 8 cm, can provide GVs closer to the gold-standard numbers.

Assessment of bony changes in temporomandibular joint in patients using cone beam computed tomography - a cross sectional study.

BACKGROUND AND AIM: The aim of this study is to evaluate the changes in the temporomandibular joint (TMJ) in patients with temporomandibular disorder (TMD) and the relationship between age, sex, and types of TMJ change using Cone Beam Computed Tomography (CBCT). METHODS AND MATERIAL: CBCT records of 200 patients (123 women and 67 men) were retrieved and assessed. Right and left TMJs were evaluated separately, resulting in a total of 400 TMJs. The images were analyzed using On demand 3D Application The radiographic findings were classified as erosion, proliferative changes mainly, including flattening and osteophytes of the condyle, sclerosis, Ely cyst, hypoplasia and hyperplasia of the condyles, ankylosis, and joint cavity. Data analysis was performed using descriptive statistics, paired T-tests, and repeated measure ANOVA (Analysis of Variance) in SPSS Software. RESULTS: The most prevalent types of condylar bony changes observed was osteophyte (63.5%) followed by flattening of the articular surface (42%), erosion (40%), ankylosis (10%) and sclerosis (10%). 7.5% of joints showed hyperplastic condyles but only 2% showed hypoplasia. The least prevalent change observed was Ely Cyst (1%). Osteophyte was the most prevalent change observed in all age groups and both sexes except for men aged 31 ~ 50, where flattening was more frequent. A statistically significant difference was found between sex and prevalence of erosion in the age group of 10 ~ 30 (P = 0.001); as well as between sex and condylar hyperplasia in the same age group. CONCLUSION: Based on the findings of this research, the prevalence of bony changes of TMJ from highest to lowest is as follows: osteophyte, flattening of the articular surface, erosion, ankylosis, sclerosis, hyperplastic condyles, hypoplastic condyles and Ely Cyst. CBCT is an accurate 3 dimensional imaging modality for assessment of TMJ bony structures.

Correlation of alveolar bone thickness and central incisor inclination in skeletal Class I and II malocclusions with different vertical skeletal patterns: A CBCT study.

INTRODUCTION: This study aimed to assess the alveolar bone thickness (ABT) and labiolingual inclination of maxillary and mandibular central incisors in patients with Class I and II skeletal patterns with normal-angle, high-angle, and low-angle vertical patterns. METHODS: The study sample consisted of 200 cone-beam computed tomography scans of patients with skeletal Class I and II malocclusions. Each group was further divided into low-angle, normal-angle, and high-angle subgroups. Labiolingual inclinations of maxillary and mandibular central incisors and ABT were measured at 4 levels from the cementoenamel junction in the labial and lingual surfaces. The Kolmogorov-Smirnov test, independent t test, 2-way analysis of variance, and Spearman's correlation test were applied for statistical analyses. RESULTS: The only significant difference between Class I and II groups regarding the ABT was found at the labial side of the maxillary central incisor, 9 mm apical to the crest. At this level, the mean ABT was 0.87 mm in patients with a skeletal Class I malocclusion, which was significantly greater than that in patients with a skeletal Class II malocclusion with a mean ABT of 0.66 mm (P = 0.02). Comparisons among the vertical subgroups revealed that on the labial and lingual sides of the mandible, as well as the palatal side of the maxilla, significantly thinner alveolar bone was found in patients with high-angle growth patterns than those with normal-angle and low-angle patterns in both sagittal groups (P <0.05). Significant weak to moderate correlations were found between ABT and tooth inclination (P <0.05). CONCLUSIONS: Significant differences in ABT covering central incisors between patients with skeletal Class I and II malocclusion are merely observed at the labial surface of the maxilla, 9 mm apical to the cementoenamel junction. Compared with patients with normal-angle and low-angle, those with a high-angle growth pattern and Class I and II sagittal relationships have thinner alveolar bone support around maxillary and mandibular incisors.

Comparison of morbidity at the donor site and clinical efficacy at the recipient site between two different connective tissue graft harvesting techniques from the palate: A randomized clinical trial.

Background: This study was conducted to compare the pain levels in patients and the clinical efficacy of grafts obtained using two techniques, namely de-epithelialized gingival graft (DGG) and subepithelial connective tissue graft (SCTG), in combination with coronally advanced flap (CAF) for the treatment of multiple adjacent gingival recessions. Methods: Twelve patients were treated using DGG+CAF on one side and SCTG+CAF on the other. The patients' pain levels at the surgical site, the number of analgesics taken on days 3 and 7, the mean root coverage (MRC), the percentage of complete root coverage (CRC), color match, and gingival thickness (GT) at the graft recipient site were evaluated 6 months after surgery. Results: The total number of analgesics taken during the 7-day period after surgery and pain levels at the surgical site from day 3 to day 7 were significantly higher in the DGG+CAF group compared to the SCTG+CAF group (P=0.001). In the 6-month follow-up, color match and CRC were significantly higher in the SCTG+CAF group, while GT was significantly higher in the DGG+CAF group. There was no significant difference in MRC between the two groups. Conclusion: The pain and analgesic consumption levels were higher in the DGG+CAF group compared to the SCTG+CAF group, and the recipient site had a weaker color match. However, this technique can lead to a greater increase in the thickness of the grafted area.

Accidental displacement of a dental implant into the nasal cavity: Report of a rare case.

Through radiographic evaluation to discover the location of a displaced implant, it was revealed that the implant had migrated to the middle meatus of the nasal cavity. The patient had no signs or symptoms, and no inflammation was observed radiographically. The implant was removed under endoscopy through the nostril.

Scalloped border as a possible diagnostic aid for differentiating jaw lesions: A pictorial essay.

Purpose: The aim of this study was to introduce a category of jaw lesions comprising cysts and tumors associated with scalloped borders. Materials and Methods: General search engines and specialized databases including Google Scholar, PubMed, PubMed Central, and Scopus, as well as an authoritative textbook, were used to find relevant studies by using keywords such as "jaw lesion," "jaw disease," "scalloping," "scalloped border," "scalloped margin," "irregular border," and "irregular margin." Out of 289 articles, 252 records were removed because they were duplicates, did not have a relevant title, or did not mention the frequency of findings described using the term "scalloped border." Finally, 37 closely related articles were chosen. Results: According to the relevant literature, scalloped borders are found most frequently in ameloblastoma, followed by simple bone cyst, central giant cell granuloma, odontogenic keratocyst, and glandular odontogenic cyst. Conclusion: The lesions most frequently reported to have scalloped borders are ameloblastoma, central giant cell granuloma, odontogenic keratocyst, simple bone cyst, and glandular odontogenic cyst.

Evaluation of maxillary arch width and palatal volume and depth in patients with maxillary impacted canine by CBCT.

Introduction: Canines are the second most common tooth in terms of impaction. Impacted teeth can be associated with some different indices of dental arch and dentoalveolar structures. The aim of this study was to evaluate maxillary arch width as well as volume and depth of palate in patients with maxillary impacted canine by cone beam computed tomography (CBCT). Methods: In this cross-sectional study, 45 CBCT images of patients with unilateral maxillary impacted canines were examined. All patients had palatally impacted canines. Three parameters of maxillary arch width, palatal volume and palatal depth were assessed using axial and sagittal incisions on the CBCT images. Then all the measurements on the impacted side were compared with the non-impacted side. Data were entered into SPSS software and paired sample t-test and Student's t-test were used to comparison. The significance level of 0.05 was considered. Results: The maxillary arch width on the impacted side was significantly less than the normal side (P < 0.001). The mean depth of the palate was 14.86 ± 3.53 mm. There was a significant correlation between canine impaction and Palatal volume (R = 0.728 and P-value< 0.001), but no significant correlation between canine impaction and Maxillary arch width was shown (R = 0.15 and p-value = 0.326). Conclusion: The impacted canine was significantly associated with a reduction in the width of the maxillary arch on the affected side, and it made no difference if the impacted side was left or right. Also, impacted canine teeth were significantly associated with volume reduction on the affected side.

Effect of the Field of View Size on CBCT Artifacts Caused by the Presence of Metal Objects in the Exomass.

Materials and Methods: In this in vitro experimental study, titanium implants, teeth with cobalt-chromium (Co-Cr) intracanal posts, and teeth with mesio-occluso-distal (MOD) amalgam restorations were placed in an empty socket of the extracted third molar of a human mandible. These metallic materials were differently arranged in the exomass (zone outside of the FOV). A polypropylene tube containing dipotassium phosphate was placed in the empty socket of the right canine tooth in a dry human mandible. CBCT scans were taken with a NewTom VGI (Verona, Italy) scanner using a 6 × 6 cm and an 8 × 8 cm FOV. The histogram tool of OnDemand software (Cybermed, Seoul, Korea) was used to select circles with a 1.5 mm diameter as the (ROI) at the center of the homogenous solution of dipotassium phosphate tube on the axial plane. The mean gray value (GV) and its standard deviation (SD) in the region of interest (ROI) were calculated (P > 0.05). The data were analyzed by SPSS 26. Results: The reduction in the size of the FOV significantly decreased the mean GV (P < 0.001). Metal objects in the exomass significantly decreased the mean GV (P < 0.001), and minimum mean GV and maximum SD were recorded for amalgam, followed by Co-Cr intracanal posts, and titanium implants. The unilateral presence of a metal object was associated with a higher mean GV and lower SD (P < 0.001). Conclusion: Using a smaller FOV increases the size of the exomass, which may negatively affect the image quality. Metal objects in the exomass decrease the GV of CBCT scans and adversely affect the image quality.

CBCT Evaluation of the maxillary palatine process as a donor site for the regeneration of periodontal defects.

Background: The maxillary palatine process (MPP) is an excellent source of autogenous bone transplants for anterior maxillary reconstruction. This research aimed to determine the quantity and quality of accessible MPP as a donor location. Methods: Cone-beam computed tomography (CBCT) scans of patients referred to the School of Dentistry were evaluated by a certified examiner. The harvestable MPP was defined as the space between the distal surfaces of maxillary first premolars. OnDemand 3D Imaging software was used to determine bone properties. SPSS software was used to investigate the following variables: Bone characteristics are correlated with age and gender, accessible volume, and palatal width and height. P<0.05 was defined as the level of statistical significance. Results: This study was performed on CBCT scans of 81 subjects (41 females and 40 males). MPP volume and palatal heights were 1.33±0.53 cm3 and 20.86±5.51 mm, respectively. Maximum bone density was observed around lateral incisors. Palatal width was 33.81±2.42 mm between canines and 41.81±2.66 mm between premolars. The MPP volume was significantly greater in males (P<0.001). Additionally, there was a positive correlation between the volume and palatal width (P<0.05). Conclusion: Within the constraints of this research, there is a limited supply of MMP accessible for use as a graft source, and it is best suited for treating localized bone lesions. The favorable link between palatal breadth and harvestable volume aids the surgeon in estimating the quantity of bone accessible during the first evaluation.

Assessment of Inferior Alveolar Nerve Position at the Region of First and Second Mandibular Molars in Dentate and Edentulous Sites Using Cone Beam Computed Tomography: A Cross-Sectional Study.

Determining the position of the Inferior alveolar nerve (IAN) is an important factor prior to any surgical procedure in the mandible such as dental implant insertion and surgical tooth extraction. The aim of this study was to compare the position of IAN in partially edentulous patients in the lower first and second molars in both missing and dentate sides. A total of 200 CBCT scans were chosen randomly and examined. On cross-sectional views, the distance between lower border of IAN canal and upper border of inferior cortex of mandible (IC) were measured at the site of dentate and edentulous mandibular first and second molar. Paired-sample t-test was used to analyze and compare measurements on right and left sides. A total of 100 males and 100 females with mean age of 46.05 ± 12.33 years were included. The IC distance measured in four pairs were as follows: Pair one: 80 cases with right missing 6 (mean ± SD = 3.73 ± 1.29 mm) and left present 6 (mean ± SD = 3.42 ± 1.20 mm), Pair two: 20 cases with right present 6 (mean = 3.20 ± 1.48 mm) and left missing 6 (mean ± SD = 3.96 ± 1.62 mm), Pair three: 54 cases of right missing 7 (mean ± SD = 3.83 ± 1.74 mm) and left present 7 (mean ± SD = 3.62 ± 1.74 mm), and Pair four: 46 case of right present 7 (mean ± SD = 3.49 ± 1.56 mm) and left missing 7 (mean ± SD = 3.84 ± 1.42). The IAN was statistically more distant from inferior cortex of mandible in the edentulous parts compared with the non-edentulous part (P < 0.05). The IAN was positioned farther from the inferior cortex of mandible in edentulous sites compared with dentate parts. Cautious consideration is essential in any surgical procedure and dental implant operations to prevent IAN injury.

Influential Factors in Buccal and Lingual Plate Perforation around Dental Implants Using Cone-Beam Computed Tomography.

This study determined the influential factors in buccal and lingual plate perforation around dental implants using cone-beam computed tomography (CBCT). In this retrospective, cross-sectional study, CBCT scans of dental implants taken for purposes not related to this study from 2017 to 2018 were retrieved from the archives of a private dental clinic. Demographic information, implant site, length, diameter, shape, and angulation, buccal and lingual plate thickness, buccolingual diameter of bone, and presence of crestal bone resorption were all assessed on CBCT scans. Data were analyzed using chi-squared, Mann-Whitney, Kruskal-Wallis, and independent t-tests. Of 604 implants, 88 had caused bone perforation in 41 females (46.6%) and 47 males (53.4%) with a mean age of 54.97 ± 13.99 years; 83% of perforations were in the maxilla; 55.7% of implants causing perforation were cylindrical and 44.3% were conical. The mean length and diameter of implants was 11.78 ± 1.91 mm, and 4.49 ± 0.76 mm, respectively; 38.9% of perforations were in the buccal and 18.2% in the lingual plate, and 42% were in the apical region. Crestal bone loss was noted in 58% of perforation cases. The mean angular deviation of implants was 19.13 ± 12.41°. Implant length and diameter had a significant association with the occurrence of perforation in the mandible (P < 0.05). Perforations had a higher frequency in the posterior maxilla, and mainly in the apical region. The buccal plate was thin in the anterior maxilla, with minimum thickness in the apical region. Lingual plate perforation had the highest frequency in the mandible.

Morphological Variations of the Posterior Mandible: Proposing a Classification for Ridge Morphology Based on Cone-Beam Computed Tomography Data.

This study sought to assess the morphological variations of the posterior mandible and propose a classification for ridge morphology based on cone-beam computed tomography (CBCT) data. This retrospective, cross-sectional study evaluated 130 CBCT scans of patients with edentulous mandibles. Qualitative variables including lingual and crestal concavity, vertical, horizontal and angular limitations, and ridge morphology were assessed at 631 sites on CBCT scans of 87 males and 43 females. A classification for ridge morphology in the posterior mandible was proposed based on the collected data. The kappa coefficient was calculated to assess the intra-observer agreement, and data were analyzed using the chi-square test and Pearson's correlation test. The frequency of lingual concavity increased from the anterior towards the posterior region relative to the mental foramen (P < 0.05). The maximum frequency of lingual concavity (11.1%) was noted at 21 mm distance from the mental foramen while its minimum frequency (4.1%) was noted at 5 mm from the mental foramen (P < 0.05). Ridge morphology, defined as ridge angulation < 15°, no lingual or crestal concavity, no limitation in width, and 8-10 mm height, had the highest frequency. Its suggested treatment plan included a 10-mm implant without width limitation or severe angulation. The majority of common morphologies had no width limitation with ridge angulation < 15°. Height limitation was only present in two of them, which can be resolved by placement of a short implant or ridge augmentation.

Does the size of an object containing dental implant affect the expression of artifacts in cone beam computed tomography imaging?

BACKGROUND: Artifacts fault image quality but handling several factors can affect it. This study was conducted to investigate the effect of object size on artifacts in cone-beam computed tomography systems. METHODS: Five phantoms, each containing a titanium implant in a sheep bone block, were fabricated of various sizes ranging from XS to XL: The M phantom was the same size as the device's field of view (FOV). The L and XL phantoms were 20 and 40% larger than the FOV while the S and XS phantoms were 20 and 40% smaller than FOV, respectively. Ballistic gelatin was used to fill the phantoms. Phantoms were scanned by NewTom VGI and HDXWill Q-FACE. The mean and standard deviation (SD) of gray values in each 120 ROI was obtained by OnDemand software. The contrast to noise ratio (CNR) was also calculated. RESULTS: The gray value in S and M phantoms were more homogenous. The lowest SD value (10.20) was found in S phantom. The highest value for SD (125.16) was observed in XL phantom. The lowest (4.47) and highest (9.92) CNR were obtained in XL and S phantoms, respectively. HDXWill Q-FACE recorded a higher SD and a lower CNR than NewTom VGI (P < 0.05). CONCLUSION: Object dimensions of the FOV size or up to 20% smaller provided better image quality. Since the dimensions of soft tissue in most patients are larger than the selective FOV, it is recommended that in CBCT artifacts studies, an object with dimensions closer to the patient's dimensions be used to better relate the results with the clinical condition, because the sample dimensions affect the amount of artifacts.

Quantitative Evaluation of Bone-Related Factors at the Implant Site by Cone-Beam Computed Tomography.

OBJECTIVES: Dental implant is a commonly used treatment modality for replacement of the missing teeth. The aim of the present study was to evaluate a number of bone-related factors at the implant site preoperatively by cone-beam computed tomography (CBCT). MATERIALS AND METHODS: A total of 400 implant sites were evaluated on CBCT images. The height, width, angle of residual ridge, thickness of cortical bone crest, and the ridge concavity were evaluated on cross sectional images at four regions: the anterior maxilla, anterior mandible, posterior maxilla, and posterior mandible. RESULTS: The highest thickness of cortical bone was observed in posterior mandible followed by anterior mandible, anterior maxilla, and posterior maxilla. In the mandible, the mean buccal concavity was higher in the anterior than in the posterior region (P = 0.0094). The measurements indicated that in both the maxilla (P = 0.0256) and mandible (P < 0.0001), the residual ridge width was lower in the anterior than in the posterior region; while the height of the residual ridge was higher in the anterior than in the posterior region in the mandible (P < 0.0001). In the maxilla, the remaining ridge angle in the anterior region was greater than that in the posterior region (P < 0.0001). CONCLUSION: Anatomical variations detected on CBCT results in personalized treatment planning considering best site and the best fixture in terms of size and position prior to implant fixture insertion.